Bayern have struggled for consistency under the Italian coach in 2016-17 and have been forced to settle for the runners-up spot in Group D of Europe's elite club competition, behind Atletico.
And while there was nothing riding on the clash against last season's beaten finalists at Allianz Arena on Tuesday, Ancelotti was nevertheless relieved to earn a positive result against Diego Simeone's tough, well-organised visitors.
"We played well, had a lot of possession and prevented counter-attacks," he said.
"We had defensive balance in this game. The result isn't important, but it gives us a lot of confidence for the coming games," he added, with a home fixture against Wolfsburg in the league coming up on Saturday.
Defender Mats Hummels was gratified by the manner in which Bayern shut down the visitors after the break.
"We only allowed a great opportunity at the beginning, but not many later," he said, referring to an early chance for Yannick Carrasco.
"We did a good job, the most important thing is that we have a defensive grasp [on the game]. We had that."